1. Field of the Invention
The present invention relates to output devices of images/video signals, and more particularly, to pixel color conversion methods and systems applied to output devices.
2. Description of the Prior Art
A printer such as an inkjet printer is capable of respectively spraying small ink droplets corresponding to specific amounts on a plurality of locations on a paper to display color and/or gray level variations of a whole image to be outputted. A typical inkjet printer or a typical multi-function printer (MFP) of the like may have a plurality of ink colors such as cyan (C), magenta (M), yellow (Y), and black (K) and may spray ink droplets corresponding to specific (C, M, Y, K) proportions on a specific location of a paper to display the color of the specific location, where blue can be displayed by utilizing cyan ink and magenta ink, red can be displayed by utilizing magenta ink and yellow ink, and green can be displayed by utilizing yellow ink and cyan ink, and theoretically, black can be displayed by utilizing cyan ink, magenta ink, and yellow ink.
On a specific location, if a certain color of ink within the cyan ink, the magenta ink, the yellow ink, and the black ink mentioned above is sprayed in excess, for example, a proportion of the certain color of ink is greater than a specific proportion, problems such as saturation may occur, which means no matter how much of the certain color of ink is increased, the color is substantially unvaried for the perception of human eyes. Similar situations may also occur regarding a laser printer. When a color laser printer applies too much toner powder corresponding to a certain color to a specific location on a paper, problems such as saturation may occur.
According to the related art, technologies such as gray component replacement (GCR) and under color removal (UCR) can be utilized for controlling the total regional ink amount or the total regional toner powder amount on the paper, where the GCR technology replaces at least one portion of colors representing details and shadows with black, while the UCR technology removes neutral gray generated by mixing cyan, magenta, and yellow in the dark portion and replaces the neutral gray by applying a proper amount of black.
It is noted that according to the related art, it is supposed that the problems mentioned above can be solved by color replacement, so the output results thereof sometimes seem to be flat or unreal in the dark portion. In addition, the output effects generated by color replacement according to the related art may vary with respect to different kinds of papers and/or different kinds of images. As a result, even after many times of adjustment or calibration, the side effects due to color replacement may still exist. Therefore, the related art does not provide a real solution to the problems mentioned above.